mollier diagrams
TRANSCRIPT
MOLLIER Diagrams
P-h CHART
PRESSURE ENTHALPY CHART
WHY IN REFRIGERATION?
• To determine accurately what is going on inside a refrigeration system
• Visualize the refrigerant behavior• Calculating capacities of refrigeration
system• Representing the condition of
equipment at any thermodynamic state.• TROUBLESHOOTING…
Classic Refrigeration system
Refrigerant regions
Constant pressure line
Constant temperature line
Enthalpy line
Constant specific volume line
Entropy line
How to plot a P-h chart?
Data From the Unit
• Low pressure P1=3 bar• High pressure P2=14 bar• Suction temperature T1=0°C• Discharge temperature T2=70 °C• Condensing temperature T3=40 °C• Temperature at TXV T4=10 °C• Evaporating temperature T5=-6 °C
P1
P2
T1
T2
T3
T4
T4
Enthalpy
Superheat
Sub cooled
High head
• Recycle cooling medium
• High cooling medium
• Poor cooling medium flow
• Fouled condenser• Non-condensable
Over charge
Low charge
• System leak• System incorrectly
charged
Liquid line restriction
• Filter dryer chocked• Blocked particle
inside the system
Poor Compressor
• Under sized compressor
• Unloaded compressor• Wrong compressor
pulley sizes• Bad compressor
valves, ring or pistons
MOLLIER Calculation• Compression ratio=High pressure/Low pressure• Flash gas=(h4-h4’)/(h1-h4’)• Refrigerating effect=h1-h4• Circulation rate of refrigerant=Refrigerating
capacity/refrigerating effect• Power at compressor=circulation rate x (h2-h1)• COP=Refrigerating capacity/power at compressor
MOTORSINGLE PHASE
SINGLE PHASE MOTOR
SINGLE PHASE MOTOR
SINGLE PHASE MOTOR
SINGLE PHASE MOTOR
SINGLE PHASE MOTOR-testing
SINGLE PHASE MOTOR-testing
SINGLE PHASE MOTOR-testing
SINGLE PHASE MOTOR-testing
SINGLE PHASE MOTOR-testing
SINGLE PHASE MOTOR-capacitor
SINGLE PHASE MOTOR-capacitor
• Run (operating) - large dimension, low capacitance 30F
• Starting - small dimension, large capacitance (can
exceed 100 F)- 5 seconds, 20
start- ups/hour
SINGLE PHASE MOTOR-capacitor
SINGLE PHASE MOTOR-capacitor
SINGLE PHASE MOTOR-capacitor
SINGLE PHASE MOTOR-capacitor
SINGLE PHASE MOTOR-capacitor
SINGLE PHASE MOTOR-capacitor
• 240V, 2A
• Xc =240/2, = 120• C =1/(2**Hz*Xc) = 1/(6.28*50*120)
= 0.00002652 F
= 26.52 F
SINGLE PHASE MOTOR-capacitor
• Normally 14 times of Amperage
• 2*14 = 28 F, if 10% 30.8 F or 25.2 F
• If out of range; change capacitor
THREE PHASE MOTOR- general point
THREE PHASE MOTOR- general point
• P =3*V*I*=1.732*220*1.7*0.8 = 520W
=1.732*380*1*0.8 = 520W
THREE PHASE MOTOR- general point
THREE PHASE MOTOR- general point
• 145W loss as heat• 375W/520W= 0.72
• 72% useful• 28% loss
THREE PHASE MOTOR- general point
THREE PHASE MOTOR- general point
THREE PHASE MOTOR- delta
THREE PHASE MOTOR- delta
THREE PHASE MOTOR- star Y
THREE PHASE MOTOR- star Y
THREE PHASE MOTOR- ?
THREE PHASE MOTOR- connections
Protection DevicesProtection Devices
THERMAL OVERLOAD RELAYS
FUSE FOR DISTRIBUTION
FUSE FOR MOTORS
Thermal RelayThermal Relay
Combination of a thermal overload relay with a contactor
Electromagnetic Overcurrent Relay
Electromagnetic Overcurrent Relay
Contactor - BreakerContactor - Breaker
Isolator - BreakerIsolator - Breaker
COMBINATIONS OF PROTECTION DEVICES
COMBINATIONS OF PROTECTION DEVICES
COMBINATIONS OF PROTECTION DEVICES
COMBINATIONS OF PROTECTION DEVICES
COMBINATIONS OF PROTECTION DEVICES
COMBINATIONS OF PROTECTION DEVICES
SWITCHESSWITCHES
• Manual switch-on pushbutton
• Manual switch-off pushbutton
• Manual on-off pushbutton
S1
S2
S3
SWITCHESSWITCHES
• Emergency stop pushbutton
• Color: Red – large mushroom head pushbutton
Limit switches Limit switches
• Normally open contact • Operated by mechanical sensor (cam roller)
• Normally open contact • Operated by level
• Normally open contact • Operated by temperature
• Normally closed contact • Operated by pressure
•
S11
S11
S11
S11
S11
P
Other switches Other switches
• Normally open contact • Operated by electromagnetic • Operating equipment designation: KM (contactor); KA
(relay)
A1
A2
KM1KM1
11
14
ELECTRICAL DIAGRAMS & WIRING
ELECTRICAL DIAGRAMS & WIRING
DIRECT ON LINE (D.O.L.)DIRECT ON LINE (D.O.L.)
• -The stator connected directly to the main supply
• -The motor starts with a high peak
• -Current peak 4 to 8 times of rated current
• -1 to 5 hp
D.O.L.D.O.L.
• Main circuit
D.O.L.D.O.L.
• Control circuit
D.O.L… forward reverse D.O.L… forward reverse
• Main circuit wiring diagram
M
L1
L2
L3
F1
KM1
A1
A2
KM2A1
A2
U1 V1 W1
F2
X11
2
3
X2
D.O.L… forward reverseD.O.L… forward reverse
• Control circuit wiring diagram
KM1 KM2
F1L1
S1
S21
S31
N
KM11
KM2
KM2 KM1
D.O.L..block diagramD.O.L..block diagram
STAR DELTA (YΔ)STAR DELTA (YΔ)
• -Motor having both ends of the three stator brought out-6 terminal
• -First step with Star- (main voltage/√3)
• -Second step with delta-normal voltage
STAR DELTA (YΔ)..power circuit
STAR DELTA (YΔ)..power circuit
STAR DELTA (YΔ).. Reverse rotation
STAR DELTA (YΔ).. Reverse rotation
STAR DELTA (YΔ)..control circuit
STAR DELTA (YΔ)..TNB control circuitSTAR DELTA (YΔ)..TNB control circuit
STAR DELTA (YΔ)..TNB power circuit
AUTO TRANSFORMER..control circuit
AUTO TRANSFORMER..control circuit
AUTO TRANSFORMER..Power circuitAUTO TRANSFORMER..Power circuit
SPECIFICATION
POWER SUPPLY
POWER SUPPLY
Connection - fan
Connection - condensing
Connection - condensing
Connection - condensing
